1. Field of the Invention
The present invention relates to an air conditioning device for use in vehicles, and particularly to an air conditioning device which changes the temperature of the blown air and the blowing rate in an optimal manner depending upon the presence or absence of solar radiation in order to maintain a comfortable atmosphere in the passenger compartment of a vehicle.
2. Description of the Related Art
In a conventional air conditioning device for vehicles, the temperature of the blown air and the like are determined depending on a preset temperature and the temperatures inside and outside the vehicle, irrespective of the presence or absence of solar radiation. Therefore, the temperature in the vehicle passenger compartment is subject to undergo a great change depending upon the presence or absence of solar radiation particularly in spring and fall when the solar radiation is strong though the atmospheric temperature is relatively low.
Therefore, it becomes necessary to detect the amount of solar radiation to properly maintain the temperature in the vehicle passenger compartment. However, if the temperature of the blown air is abruptly lowered because the heat is received in large amounts from the solar radiation, the passengers who are directly exposed to the blown air will feel excessively chilled and will find it uncomfortable.
A variety of proposals have heretofore been offered in an attempt to solve the aforementioned problems inherent in the conventional air conditioning devices for vehicles as disclosed in, for example, Japanese Examined Utility Model Publication No. 59-34497 and U.S. Pat. No. 4,890,460. According to these prior arts, the temperature of the air blown into the vehicle passenger compartment is controlled by the use of a solar radiation sensor. Namely, the temperature of the blown air only is controlled, but a comfortable environment is not created in the vehicle passenger compartment by controlling both the temperature of the blown air and the blowing rate simultaneously.